1. Field of the Invention
This invention relates to a disk changer in a device for recording data on and reproducing data from a disk-shaped recording medium such as a CD and a CD-ROM (hereinafter referred to merely as "a disk", when applicable) which disk changer accommodates a plurality of disks and automatically loads a selected disk in a disk driving section which includes a data recording and reproducing unit such as an optical pickup, and more particularly to a disk changer in which a plurality of disks are laid on carriages, and the disk which is being played is automatically replaced with another one by moving the carriages horizontally and vertically.
2. Related Art
A conventional disk changer which is simple in structure for loading and automatically exchanging three or four disks is shown in FIG. 29. That is, it has a rotary disk tray, and is called "a carrousel type disk changer (cf. Unexamind Japanese Utility Model Publication No. 121045/1992). The carrousel type disk changer operates as follows: A disk tray 101 on which a plurality of disks are set is turned to select one of the disks, and the disk thus selected is moved to a disk driving section which includes an optical pickup. In the upper surface of the disk tray 101, a plurality of recesses 102, 102 and 102 in each of which a disk placed are formed in such a manner that they are not overlapped with one another. At the disk reproducing position, the disk drive section (not shown) is moved vertically; that is, it is moved through a through-hole 103 formed in the recess 102 to hold the disk in cooperation with a clamper (not shown) which is arranged above the disk tray 101. In the disk changer, disk replacement is carried out as follows: While the disk driving section is held retracted below the disk tray 101, the disk tray 101 is turned to select a disk, and move it to the disk reproducing position.
In the carrousel type disk changer, a plurality of disks are loaded on one disk tray 101 in such a manner that they are not overlapped with one another as was described above. Hence, as the number of disks to be loaded on the disk tray 101 increases, the width and length (or external dimensions) of the device is increased; that is, the space occupied by the disk changer is increased. Even in the case where only three disks are loaded on one disk tray, both the width and length of the disk changer are each at least twice as long as the diameter of each disk, and the area is more than four times that of each disk.
In the case of the carrousel type disk changer, in order prevent the disk tray 101 from rubbing the chassis 104 of the disk changer body when the disk tray is turned, it is essential that the disk tray 101 in high in flatness, being free from a warp. In order to make the disk tray high enough in rigidity, or to make it free from a warp, the disk tray has reinforcing ribs, and accordingly its apparent thickness for height) is large.
On the other hand, the disk changer is so designed that the disk driving section including the optical pickup is moved up and down with respect to the disk. Therefore, it needs a mechanism for moving the disk driving section, and some space in the direction of height. As is apparent from the above description, the carrousel type disk changer in disadvantageous in that it is relatively large in width, length, and height.
In addition, in order that the disk tray 101 may be turned stably and smoothly on the chassis while being kept horizontal, the disk tay 101 is provided with supporting parts such as roller; that is the disk changer in large in the number of components, which results in an increase in the manufacturing cost.
For rationalization, the disk tray is formed as one unit by molding resin. Since it is a large molded product which is high in flatness, the resultant disk changer is high in manufacturing cost.
On the other hand, a cartridge type disk changer has been proposed in Japanese Unexamined Patent Publication Hei 4-38657; that is a plurality of disks are loaded therein in such a manner that they are stacked in a cartridge (or stocker). The cartridge type disk changer is advantageous in that at number of disks can be loaded therein when compared with the carrousel type disk changer; however, it is still disadvantageous in that, during reproduction, it is impossible to take out or replace the disk, because the disks are accommodated in the cartridge (or stocker) behind the pickup.